There has been an explosive increase in the availability and use of organic adhesives, sealants and coatings. Adhesion is a basic requirement common to the application of these materials whether their function is structural, protective or decorative. Reliable adhesion depends upon cleaning and preparation of the adhering surface. The purpose of surface preparation is to remove weak surface layers of soils and corrosion products, usually oxides, and to generate a cohesively strong and wetable surface layer that has a high affinity for adhesives, coatings and sealants. The other important requisites for the surface treatment is that the newly generated surface layer must be environmentally stable under the combined influence of stress, elevated temperature and moisture. Dorsey U.S. Pat. No. 3,616,310 teaches surfaces preparation of aluminum for bonding using an aqueous bath of 7 to 12 percent sulfuric acid and 0.25 to 0.80 percent chromic acid with the aluminum anodized at 10 to 30 amps per square foot at a temperature of about 68.degree. F to 86.degree. F. It is known to prepare an environmentally stable aluminum surface for bonding by anodizing in an aqueous sulfuric chromic acid bath at 130.degree. F to 160.degree. F and 1 to 2.5 volts, for from 2.5 to 20 minutes. Batcheller U.S. Pat. No. 2,409,097 shows the use of an aqueous acid bath of 15 to 55 weight percent sulfuric acid and 2 to 20 weight percent chromic acid to electro-chemically polish stainless steel alloys using the steel as an anode with a bath temperature of above 160.degree. F and a current flow of 11/2 to about 15 amperes per square inch of anode. It is also known to prepare stainless steel for bonding by anodic etching in an aqueous sulfuric acid bath at 6 volts for 90 seconds in a 75.degree. F bath. There are other known processes for preparing a stainless steel surface for bonding and generally all of these processes produce a bonding surface with satisfactory initial mechanical strengths, but the difficulty has been to produce an environmentally stable bond. It was discovered an environmentally stable stainless steel surface for bonding is obtained by anodizing stainless steel with a current flow of from 0.3 to 6 amperes per square foot in an aqueous sulfuric acid or an aqueous sulfuric chromic acid bath.